Toxins from the algae Gymnodinium breve and Pyrmnesium parvum will be purified by using high pressure liquid chromatography techniques. Identification of the toxic principles will be done by a combination of infrared and nuclear magnetic resonance spectroscopy, gas-liquid chromatography, and ion desorption mass spectroscopy. These structural studies will be correlated to analyses on the physiological activity of the toxins on the giant axon of the squid and the Ca ions-dependent ATPase of sarcoplasmic reticulum vesicles.